Custom frame's published properties disappear on form file reopening

Question

I'm using TFrame as base class for a compound component which is registered in the IDE. When I pick the component from the palette and I add it into a form/frame, everything seems to works good. The next time I open the form/frame, the frame component appears as a common frame, like if the component is unregistered from the IDE, I mean that:

• All custom published properties are no more visible in the Object Inspector.
• Only published properties inherited from TFrame are still visible in the Object Inspector.
• Subcomponents can be clicked and moved inside the frame.

Furthermore, if the property had a value, I get the following error:

Error reading MyComponent1.MyProperty: Property MyProperty does not exists. Ignore the error and continue? NOTE: Ignoring the error may cause components to be deleted or property values to be lost.

Step by step example:

• I've created and compiled a "Designtime and Runtime" package. (Note that, using Delphi 2007, I've obtained the TFrameModule class as explained in this Ondrej Kelle's post).

Code:

  TMyComponent = class(TFrame)
  private
    FMyCaption : TCaption;
    { Private declarations }
  public
    { Public declarations }
  published
    property MyCaption : TCaption read FMyCaption write FMyCaption;
  end;

....

procedure Register;
var
  delphivclide: THandle;
  TFrameModule: TCustomModuleClass;
begin
  RegisterComponents('MyComponents', [TMyComponent]);

  //registering custom module for TMyComponent
  delphivclide := GetModuleHandle('delphivclide100.bpl');
  if delphivclide <> 0 then
  begin
    TFrameModule := GetProcAddress(delphivclide, '@Vclformcontainer@TFrameModule@');
    if Assigned(TFrameModule) then
      RegisterCustomModule(TMyComponent, TFrameModule);
  end;
end;

• I've added the folder which contains dcu and dcp files to Tools -> Options -> Library - Win32 -> Library path

• I've added the folder which contains the bpl file to the PATH environment variable.

• I've installed the package in the IDE and restarted it.

• I've created a new "Runtime" package with a form in which I've placed a component of TMyComponent class.

• The component is appeared as expected and I've set MyCaption property to 'AAA'.

• Then I've saved the form and closed the IDE.

• After that I've restarted the IDE, on reopening the same form file, I get the following error:

• I've also tried to follow the same steps without setting any value to the property and I've noticed that the property disappears from the Object Inspector:

Further informations:

• The MyCaption property appear in the Object Inspector each time the component's package is recompiled and the IDE is restarted. I can see it in the Object Inspector until the next time I close and restart the IDE, then it disappears again.

• I've reproduced the same problem using DelphiXE7, passing 'delphivclide210.bpl' instead of 'delphivclide100.bpl' to the GetModuleHandle function in the Register procedure.

• It doesn't seems related to the OS, I've reproduced it on Windows 10 and on Windows XP.